CoMaps can display 3D buildings (example: way/201611261 has multiple building parts with different heights). I want to add height data for parts of buildings in my local area but I obviously can’t go around measuring every building. Is there something I can use like a lidar dataset or similar to get height data? Or should I just not bother with tagging height?
Something easier is tagging building:levels instead. Most 3D renderers support this tag, usually estimating 3 meters each floor.
For many parts of Europe LIDAR data is available:
For NL we have AHN. That data is used by the TU Delft to create 3DBAG to reconstruct 3D building models and that data has been used to give buildings in Amsterdam it’s height.
For France there is LiDAR HD, not sure about the license.
If something is made of geometric units, e.g. bricks, a more detailed estimate can be made.
For example, in the UK and Ireland, the vast majority of bricks are 215 x 100 x 65 mm. If one includes the mortar joint, the long face of the brick will normally be 225 x 75 mm. If the façade is 40 bricks high (40 being a manageable number to count), then that is 3 metres. With taller buildings, you can break up the counting by counting from the ground to a window, count for the height of the window, count for the height to the window above, etc. So called “Dutch bricks” are 190 x 90 x 40 mm. If one includes the mortar joint, the long face of the brick will normally be 200 x 50 mm. I’m not sure what dimensions are actually used in the Netherlands.
Ordinary doors tend to be about 900 x 2100 mm and most adults tend to be between 1.5 and 1.8 metres tall. Of course, this will vary between the Netherlands (taller than average) and say South East Asia (shorter than average).
Ordinary cars tend to be about 1.3-1.5 metres high and 1.5-2.0 metres wide. 4x4s, etc. will be taller. A double-deck city bus is about 4.5 metres.
License is fine, DEM and DSM are available as background image on JOSM and iD.
@h234a2hm feel free to check the data with Terrain Viewer
Hi,
One method I’m using is by photography.
Eg. taking a photo orthogonally to the building.
Then I can measure width/height in pixels and apply the ratio to the real width of the building which I can measure in JOSM.
You can also use a laser based distance meter to measure the height.
Intercept theorem - Wikipedia is another option.
Is there no way to query pixels individualy?
In theory, sure it’s simple the difference between the two models.
Code of Terrain Viewer is public, you can propose a PR, or request it through a ticket.
Thanks for mentioning terrain-viewer indeed probably a good fit for the OP use-case!
elevation-picker is indeed a good tool for this, you can take the measurement on whatever underlying source is being used. The default terrain source, Mapterhorn is the best aggregated, high-resolution open-data from national mapping agencies. You could also chose to load samples - a lot of nation-wide terrain sources (DSM/DTM) are landing later this week for various countries - or even import your own custom terrain source (COG local/remote, TMS Terrarium, WMS etc).
Either do a 2D straight profile, or just pick elevation at top-most point of the building and neighboring ground point to see reported deltaZ.
OSM Building Height Enrichment has an interesting approach. I haven’t gotten to fully verify a series of samples, but I think it’s generally reliable.